Bonding pad for anti-peeling property and method for fabricating the same

ABSTRACT

A bonding pad includes a conductive layer formed over an insulation layer, and a dummy pattern penetrating the insulation layer and stuck in the conductive layer, wherein a bonding process is performed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention is a Divisional Application of U.S. patentapplication Ser. No. 12/164,773, filed Jun. 30, 2008, which claimspriority of Korean patent application number 2007-0133331, filed on Dec.18, 2007, the which is incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a method for fabricating asemiconductor device, and more particularly, to a bonding pad forpreventing a pad peeling and method for fabricating the same.

Generally, in a process for fabricating semiconductor devices,particularly in a package process (in a wire bonding process), a metalpad of a bonding pad unit disposed in a chip is electrically connectedto an external device through a leadframe. For instance, when performingthe wire bonding, a ball bonding is performed over the metal pad. Thebonding pad unit where the ball bonding is performed includes aninsulation layer among a plurality of metal layers.

FIG. 1 is a cross-sectional view of a typical bonding pad.

FIG. 2 is microscopic pictures showing limitations generated whenperforming a typical wire bonding.

Referring to FIG. 1, a typical bonding pad includes first to third metallayers 11, 13 and 15. A first insulation layer 12 is formed between thefirst metal layer 11 and the second metal layer 15. A second insulationlayer 14 is formed between the second metal layer 13 and the third metallayer 15. A passivation layer 16 is formed over the third metal layer 15to expose a portion of the third metal layer 15 where the bonding isperformed.

Referring to FIG. 2, when performing the wire bonding, the bonding pad,i.e., the third metal layer 15, may be peeled off and even the secondinsulation layer 14 may be peeled off together. That is, a pad peelingoccurs. The pad peeling of the second insulation layer 14 is generatedbecause of the third metal layer 15 being damaged when the passivationlayer 16 for exposing the third metal layer 15 is etched to therebydecrease a thickness of the third metal layer 15. More specifically, thethird metal layer 15 with the decreased thickness is not capable ofstanding against power or stress applied thereto during a subsequentwire bonding process. Thus, the third metal layer 15 is cracked tothereby cause the pad peeling. Furthermore, the crack in the third metallayer 15 is transmitted to the second insulation layer 14 to deterioratethe second insulation layer 14. As a result, the pad peeling grows evenworse. The pad peeling causes a bonding failure to thereby dropthroughput of the semiconductor devices.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to providing a bondingpad for preventing pad peeling and a method for fabricating the same.

In accordance with at least a disclosed embodiment, there is provided abonding pad including a conductive layer formed over an insulationlayer, and a dummy pattern penetrating the insulation layer and stuck inthe conductive layer, wherein a bonding process is performed.

In accordance with another disclosed embodiment there is provided amethod for forming a bonding pad. The method includes forming a dummypattern, forming an insulation layer to cover the dummy pattern,selectively etching the insulation layer to form a recess patternprotruding a portion of the dummy pattern from the insulation layer, andforming a conductive pattern where a bonding process is performed tocover the dummy pattern protruded from the insulation layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a typical bonding pad.

FIG. 2 is microscopic pictures showing limitations generated whenperforming a typical wire bonding.

FIG. 3 is a plane view of a bonding pad in accordance with an embodimentof the present invention.

FIG. 4 is a cross-sectional view of the bonding pad of FIG. 3 cut alongX-X′ line.

FIGS. 5A to 5F are cross-sectional views describing a method for forminga bonding pad in accordance with an embodiment of the present invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Embodiments of the present invention relate to a bonding pad forprevented pad peeling and method for fabricating the same.

An embodiment of the present invention discloses a method for protectinga bonding pad from being peeled off when a wire bonding process isperformed and power or stress is applied to the bonding pad. Theembodiment may be applied to a memory pad formation process including aball bonding performed on the bonding pad for packaging. The embodimentmay also be applied to any other methods for preventing the pad peelingfrom occurring during a formation of a large pattern like the bondingpad.

In bonding pad including a plurality of metal layers and an insulationlayer therebetween, a top metal layer and another metal layer below thetop metal layer are formed in one body. Thus, it is possible to preventthe peeling of the bonding pad.

FIG. 3 is a plane view of a bonding pad in accordance with an embodimentof the present invention.

FIG. 4 is a cross-sectional view of the bonding pad of FIG. 3 cut alongX-X′ line.

Referring to FIGS. 3 and 4, a bonding pad is formed over the insulationlayer 22. The bonding pad includes a dummy pattern 21. The dummy pattern21 penetrates the insulation layer 22 and is partly stuck in theconductive pattern 25. The insulation layer 22 may include a recesspattern 23. The recess pattern 23 may include a region where theconductive pattern 25 is in contact with the dummy pattern 21. Also, thebonding pad may include an adhesion layer 24 formed on sidewalls of therecess pattern 23 in a spacer shape. The adhesion layer 24 improvesadhesion characteristics between the conductive pattern 25 and theinsulation layer 22.

Herein, a portion of the dummy pattern 21 is stuck in a lower portion ofthe conductive pattern 25. The dummy pattern 21 penetrates and protrudesfrom the insulation layer 22. The conductive pattern 25, where thebonding is performed, covers the protruded dummy pattern 21. That is,the conductive pattern 25 for the bonding and the dummy pattern 21 areformed in one body to increase an adhesion power therebetween. Thus, thepeeling of the bonding pad is prevented. To increase the adhesion powerbetween the conductive pattern 25 and the dummy pattern 21, the dummypattern 21 protrudes approximately 25% to approximately 75% thereof fromthe insulation layer 22.

The dummy pattern 21 may be formed to have a plurality of slits arrangedin a matrix form. By increasing a contact region between the conductivepattern 25 and the dummy pattern 21, adhesion power therebetweenincreases. Thus, the peeling of the bonding pad can be prevented.

The dummy pattern 21 penetrates the insulation layer 22 to protrude aportion thereof from the insulation layer 22. Thus, the adhesion area isreduced to effectively prevent the peeling of the bonding pad. An oxidelayer, e.g., a Spin On Glass (SOG) layer for the insulation layer 22below the bonding pad contains impurities such as carbon (C) so thathardness is low. Layer quality is easily lowered by power or stressapplied on the bonding pad when the wire bonding is performed.Therefore, it is possible to maintain the layer quality of theinsulation layer 22 and prevent the pad from being peeled off byreducing the adhesion between the conductive pattern 25 and theinsulation layer 22.

Furthermore, the bonding pad may include a passivation layer 26 exposinga surface of the conductive pattern 25 in the bonding pad unit.

The conductive pattern 25, the dummy pattern 21, and the adhesion layer24 may be selected from a group consisting of aluminum (Al) layer, acopper (Cu) layer, and a tungsten (W) layer. By preventing the padpeeling of the bonding pad, throughput of the package increases. As aresult, production cost decreases.

In this embodiment, the bonding pad is applied to a Tri LayerMetallization (TLM) structure including first to third metal layer andan insulation layer formed among the metal layers.

FIGS. 5A to 5F are cross-sectional views describing a method for forminga bonding pad in accordance with an embodiment of the present invention.

Referring to FIG. 5A, a first insulation layer 32 is formed over a firstmetal layer 31. The first metal layer 31 functions as a line and may beselected from the group consisting of Al layer, a Cu layer, and a Wlayer.

The first insulation layer 32 is an Inter Metal Dielectric (IMD) layerand may include an oxide layer. It is within the scope of the inventionthat the first insulation layer 32 may be a low-k layer. Thus, aparasitic capacitance between a second metal layer 34 and a dummypattern 34A formed through a subsequent process is established.

The first insulation layer 32 is selectively etched to form a contacthole exposing an upper portion of the first metal layer 31. The contacthole is filled with a conductive layer to form a first plug 33electrically connecting the first metal layer 31 to the second metallayer 34.

The second metal layer 34 is also formed over the first insulationlayer. The second metal layer 34 is selectively etched to form aplurality of dummy patterns 34A. The second metal layer 34 functions asa line and may be selected from the group consisting of Al layer, a Culayer, and a W layer.

Herein, the dummy pattern 34A does not function as a line. The dummypattern 34A is formed to be electrically divided with the second metallayer 34. Furthermore, the dummy pattern 34A increases contactdimensions between a subsequent conductive pattern for the bondingprocess and the dummy pattern 34A to increase the adhesion powertherebetween. Thus, the dummy pattern 34A is formed to have a pluralityof slits arranged in a matrix form. It is also within the scope of theinvention to form the dummy pattern 34A to have other various shapesthat can increase the contact dimensions between the subsequentconductive pattern and the dummy pattern 34A.

A second insulation layer 35 is formed to cover the second metal layer34 and the dummy pattern 34A. The second insulation layer 35 is an InterMetal Dielectric layer (IMD) and may be an oxide layer. The secondinsulation layer 35 may be a low-k layer. Thus, parasitic capacitancebetween the second metal layer 34 and the dummy pattern 34A formedthrough a subsequent process is established.

Referring to FIG. 5B, the second insulation layer 35 is selectivelyrecess etched to form a recess pattern 36 exposing an upper surface ofthe dummy pattern 34A. When the recess pattern 34 is formed, a contacthole 37 exposing an upper surface of the second metal layer 34 can besimultaneously formed. The contact hole 37 forms a second plugelectrically connecting a subsequent third metal layer and the secondmetal layer 34. A linewidth of the contact hole 37 is smaller than thatof the recess pattern 36.

A conductive layer 38 for a plug is formed over the second insulationlayer 35. The conductive layer 38 may be a metal layer such as atungsten (W) layer. Since a linewidth of the recess pattern 36 isgreater than that of the contact hole 37, the contact hole 37 iscompletely filled with the conductive layer 38. At the same time, theconductive layer 38 is formed along a surface of the recess pattern 36.

Referring to FIG. 5C, an etch-back process is performed to expose asurface of the second insulation layer 35. Thus, a second plug 38A isformed to fill the contact hole 37. An adhesion layer 38B is formed on asidewall of the recess pattern 36 to have a spacer shape. The adhesionlayer 38B can improve adhesion characteristics between the conductivepattern and the second insulation layer 35.

Referring to FIG. 5D, a photoresist pattern 39 is formed over the secondinsulation layer 35 to open the region where the recess pattern 36 isformed. The second insulation layer 35 is etched using the photoresistpattern 39 and the adhesion layer 38B as an etch barrier to protrude aportion of the dummy pattern 34A from the second insulation layer 35.The dummy pattern 34A protrudes approximately 25% to approximately 75%thereof from the second insulation layer 35.

A portion of the dummy pattern 34A protrudes from the second insulationlayer 35 to form a subsequent conductive pattern and the dummy pattern34A in one body. A removal process is performed to remove thephotoresist pattern 39.

Referring to FIG. 5E, a third metal layer is formed over the secondinsulation layer 35 to cover the dummy pattern 34A. The third metallayer is selectively etched to form a conductive pattern 40 for thebonding process. The conductive pattern 40 may be selected from thegroup consisting of Al layer, a Cu layer, and a W layer. The conductivepattern simultaneously functions as a line and a bonding pad.

Since the conductive pattern 40 is formed to cover the protruded dummypattern 34A, the contact region between the second insulation layer 35.An oxide layer, e.g., a spin on gas (SOG) layer for the secondinsulation layer 35 below the bonding pad contains impurities such ascarbon (C) so that hardness is low. Layer quality is easily lowered bypower or stress applied on the bonding pad when the wire bonding isperformed. Therefore, it is possible to maintain the layer quality ofthe second insulation layer 35 and prevent the pad from being peeled offby reducing the adhesion between the conductive pattern 40 and thesecond insulation layer 35. A passivation layer 41 is formed over aresultant structure including the conductive pattern 40. The passivationlayer 41 is selectively etched to expose the conductive pattern 40.Herein, the conductive pattern 40 may be damaged so that a thickness ofthe conductive pattern 40 may be reduced. When the thickness of theconductive pattern 40 is reduced, a crack may appear therein due topower or stress during a subsequent wire bonding process. However, inthe bonding pad of as in the disclosed embodiments of the presentinvention, the conductive pattern 40 is formed to cover the protrudeddummy pattern 34A. Thus, the thickness of the conductive pattern 40 maybe high. That is, the bonding pad of the disclosed embodiments of thepresent invention may be thicker than the typical bonding pad. Eventhough a portion of the conductive pattern 40 is damaged during an etchof the passivation layer 41 for exposing the conductive pattern 40 inthe bonding pad, the crack does not appear in the conductive pattern 40by the power or the stress applied during the subsequent process.

Referring to FIG. 5F, the wire bonding process is performed on theconductive pattern 40. The wire bonding may be a ball bonding 42process. To increase the adhesion power between the conductive pattern40 and the ball bonding 42, the power is applied in a perpendiculardirection to the conductive pattern 40 or physical oscillation may beapplied during the wire bonding process.

As described, the conductive pattern 40 and the dummy pattern 34A areformed in one body. Thus, it is possible to prevent the peeling of thebonding pad and increase a throughput of the package.

In the disclosed embodiments, the dummy pattern 34A protruding from theinsulation layer 35 is formed to cover the conductive pattern 40 wherethe bonding process is performed. Since the dummy pattern 34A and theconductive pattern 40 are formed in one body, the peeling of the bondingpad can be prevented.

A portion of the dummy pattern 34A is protruded from the insulationlayer 35 to reduce the contact dimensions between the insulation layer35 and the conductive pattern 40. As a result, the peeling of thebonding pad can be prevented.

Also, the conductive pattern 40 is formed to cover the dummy pattern 34Aprotruding from the insulation layer 35. The thickness of the conductivepattern 40 increases and the crack is caused less in the conductivepattern 40 when the passivation layer 41 is etched to expose theconductive pattern 40. As a result, the peeling of the bonding pad canbe prevented.

Furthermore, the adhesion layer 38B is formed to have a spacer shape toincrease the adhesion force between the insulation layer 35 and theconductive pattern 40. Thus, it is possible to prevent the peeling ofthe bonding pad during the wire bonding process.

While the present invention has been described with respect to thedisclosed embodiments, the above embodiments of the present inventionare illustrative and not limitative. It will be apparent to thoseskilled in the art that various changes and modifications may be madewithout departing from the spirit and scope of the invention as definedin the following claims.

1. A bonding pad, comprising: dummy patterns; an insulation layer thatcovers the dummy patterns; a recess pattern formed by selectivelyetching the insulation layer, wherein upper portions of the dummypatterns are protruded from the etched insulation layer, and wherein theetched insulation layer remains between lower portions of the dummypatterns; and a conductive pattern that covers the dummy patterns tofill spaces between the protruding upper portions of the dummy patternsto form the conductive pattern and the dummy patterns in direct physicalcontact, wherein the conductive pattern is later used in a bondingprocess.
 2. The bonding pad of claim 1, further comprising an adhesionlayer formed on sidewalls of the recess pattern.
 3. The bonding pad ofclaim 2, wherein the adhesion layer is formed to have a spacer shape. 4.The bonding pad of claim 1, wherein the dummy patterns has are formed ina matrix shape, the matrix shape having a plurality of slits therein. 5.The bonding pad of claim 1, wherein the dummy patterns protrudeapproximately 25% to approximately 75% of a vertical height of the dummypatterns above the surface of the etched insulation layer disposedbetween the dummy patterns.
 6. The bonding pad of claim 1, wherein eachof the conductive pattern, the dummy patterns and the adhesion layerincludes a metal layer.
 7. The bonding pad of claim 1, wherein each ofthe conductive pattern, the dummy patterns and the adhesion layerincludes one selected from a group consisting of an aluminum (Al) layer,a copper (Cu) layer, and a tungsten (W) layer.